The present invention relates to a method of and a system for a lock-up control during a gear shifting in an automatic transmission.
Japanese Patent Application First (unexamined) Publication No. 63-9771 discloses a lock-up control during a gear shifting in an automatic transmission. According to this known control, beginning and ending of a temporary release of a lock-up clutch are determined in response to a ratio of an input revolution speed indicative signal and an output revolution speed indicative signal.
An object of the present invention is to improve a lock-up control of the above kind such that a delay in release of the lock-up clutch which would cause substantial shift shock is prevented even if in certain circumstances it is difficult to determine a beginning of an intended or desired temporary release of the lock-up clutch.